DE 37 42 824 A1 discloses a pump having a pump piston which is guided in a bushing within the pump housing. Remote from the pump piston and the compression chamber, the bushing accommodates the valve seat for the pressure valve. The suction valve is arranged within the compression chamber at the pump piston and is connected to a pressure fluid source through a piston-side supply channel. The pressure valve is arranged in a retaining member which is secured to the bushing by way of indentations. The bushing also includes the valve seat for accommodating the pressure valve. It is disadvantageous that the retaining member along with the bushing, as a preassembled unit, can be checked and configured only outside the pump housing which, among others, impairs the interchangeability of the individual parts.
Therefore, an object of the present invention is to improve a pump of the previously mentioned type so that a construction as simple and compact as possible is achieved. Another object of the present invention is to have a pump construction such that leakage test of the pressure valve is permitted both outside and inside the pump housing, and, if replacement is necessary, ease of such replacement of individual parts, such as replacement of the pressure valve or the valve seat member, is ensured if leakage occurs during testing.
This object is achieved according to the present invention in that the peripheral surface of the valve seat member facing the cover has a conical chamfer onto which an annular projection of the cover is movable into sealing abutment and is radially expandable to provide a press fit engagement.